JPH04316875A - Sheet feed mechanism - Google Patents

Abstract

PURPOSE:To prevent a printing position from becoming offset due to a difference in the thickness of a sheet and a change in the feed direction of the sheet. CONSTITUTION:An eccentric shaft 4 has an eccentric rotating center at both ends and is held by a side frame 11. In addition, the eccentric shaft 4 is held by a gap adjustment lever 1 with gear fixed to one end of a guide shaft 3 and a side frame 11 with gear which becomes engaged with the gear. An under paper guide 5 has a rotating center on the sheet introduction side for a printing web and is held by the side frame 11. In addition, the under paper guide 5 causes the sheet discharge side for the printing web to come in contact with the eccentric shaft 4 and also causes a gap between the under paper guide and an upper guide 6 with the help of a gap adjustment lever 1. Further, guide ribs which follows the contour of the lower surface of the upper paper guide 6 can be pressed against the lower surface through a spring and thus the printing web can be retained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed mechanism, and more particularly to an improvement in a paper feed mechanism for a serial printer.

0002

2. Description of the Related Art Conventionally, in a paper feed mechanism employing a so-called push tractor, in which a tractor of this type is provided on the paper insertion side of continuous printing paper, as shown in FIG. 6 or 7, continuous printing paper 12 An upper paper guide 6 is fixed to a side frame (not shown) to guide the paper to the printing position, and an under paper guide 6 is fixed to the side frame with a predetermined gap provided between the upper paper guide 6 and the upper paper guide 6. - A paper guide 5 was provided, and the continuous printing paper 12 was guided through the gap between these two paper guides.

0003

[Problems to be Solved by the Invention] In the conventional paper feeding mechanism described above, since the gap between the upper paper guide and the lower paper guide is constant, the paper feeding mechanism is not supplied by the push tractor 10 as shown in FIG. As shown in FIG. Misalignment occurs between the printing position and the printing paper. Another disadvantage is that misalignment occurs due to differences in paper thickness. In particular, when the direction of paper feed for continuous printing paper is changed from forward to reverse, or conversely from reverse to forward, a large discrepancy occurs, which requires firmware changes and the paper feed mechanism. The disadvantage is that it is complicated.

0004

[Means for Solving the Problems] A first invention provides a carriage that carries a print head and performs printing while moving parallel to the longitudinal direction of a platen while being guided by a guide shaft fixed to a side frame, and a side frame. an upper paper guide and an under paper guide that are fixed to and guide the continuous printing paper to the printing position of the print head; and an endless belt that is provided on the insertion side of the continuous printing paper and supplies the continuous printing paper. In a paper feed mechanism for a printer equipped with tractors on the left and right sides, the first paper feed mechanism has an eccentric rotation center at both ends, is rotatably held by a side frame, and is fixed to one end of a guide shaft.
a swingable gap adjustment lever having a gear;
an eccentric shaft rotatably held by the side frame and having a second gear that engages with the gear; an eccentric shaft having a rotation center on the paper insertion side of the continuous printing paper and swingably held by the side frame; It is equipped with an under paper guide that keeps the paper ejection side of continuous printing paper in constant contact with the eccentric shaft.

[0005] Also, the second invention includes a support plate held by the side frame, a plurality of springs supported at one end by the support plate, and an upper paper support plate supported by the other ends of the plurality of springs. Opposite the lower part of the guide,
and a plurality of guide ribs shaped like a paper guide.

[0006]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing a first embodiment of the present invention. In FIG. 1, the paper feeding mechanism of this embodiment includes a gap adjustment lever 1, a gear 2, a guide shaft 3, an eccentric shaft 4, an under paper guide 5, an upper
Consisting of a paper guide 6, a print head 7, a carriage 8, a platen 9, a push tractor 10, and a side frame 11, these inner guide shafts 3, under paper guides 5, and upper paper guides 6
, print head 7, carriage 8, platen 9, push tractor 10 and side frame 11 are similar in arrangement and function to the conventional embodiment.

The push tractor 10 is connected to a drive (not shown) and supplies continuous printing paper (not shown). The guide shaft 3 has an eccentric center of rotation, is passed through a slide hole of the carriage 8 on which the print head 7 is mounted, and is fixed to the left and right side frames 11. A gap adjustment lever having a gear shape is attached to one end of the guide shaft 3. 1 is fixed. The eccentric shaft 4 has an eccentric rotation center and is rotatably held by the left and right side frames 11. A gear 2 is attached to one end of the eccentric shaft 4 and engages with the gear portion of the gap adjustment lever 1. ing.

The upper paper guide 6 is an upper guide plate that guides the continuous printing paper to the printing position of the print head 7, and is fixed to the left and right side frames 11. Further, the under paper guide 5 is a lower guide plate that guides the continuous printing paper to the printing position of the print head 7, and is swingably held with its center of rotation on the insertion side. The lower surface of the under paper guide 5 on the continuous printing paper discharge side is in constant contact with the eccentric shaft 4. By operating the gap adjustment lever 1, the guide shaft 3 having an eccentric rotation center moves the position of the carriage 8, that is, the position of the print head 7 back and forth, and at the same time moves the position of the print head 7 back and forth, following the rotation of the eccentric shaft 4.・As the paper guide 5 swings in the vertical direction, the upper paper guide 6
Change the gap between

FIG. 2 is a partial side view showing how the gap is adjusted when using thin continuous printing paper, and FIG. 3 is a partial side view showing how the gap is adjusted when using thick continuous printing paper. FIG. In FIG. 2, when thin continuous printing paper is used, by operating the gap adjustment lever 1, the gap size a between the print head 7 and the platen 9, and the distance between the under paper guide 5 and the upper paper If you simultaneously reduce (narrow) the gap dimension b with the guide 6 and use thick continuous printing paper,
As shown in FIG. 3, the gap size a and the gap size b are simultaneously increased (widened) by a similar operation.

Next, other embodiments of the present invention will be explained.

FIG. 4 is a perspective view showing a second embodiment of the present invention.

FIG. 5 is a partial side view of FIG. 4. 4 and 5, the push tractor 10, platen 9, print head 7, and carriage 8 of the paper feed mechanism of this embodiment are shown.
, guide shaft 3 and under paper guide (
(not shown) are similar in arrangement and function to conventional embodiments.

Upper paper guide 2 of this embodiment
This upper paper guide 20
A support plate 22 is attached to left and right side frames (not shown) in parallel to the left and right side frames. Further, the guide rib 21 has a shape that follows the lower surface of the upper paper guide 20,
It is supported by a support plate 22 via a spring 23 having a predetermined elasticity. This guide rib 21 guides the continuous printing paper 12 to the upper paper guide 20 by the elasticity of the spring 23.
A plurality of them are provided on the support plate 22 at predetermined intervals.

[0015]

[Effects of the Invention] As explained above, according to the paper feeding mechanism of the first invention, the gap between the upper paper guide and the lower paper guide can be easily adjusted to an appropriate gap by operating the gap adjustment lever. Even if the continuous printing paper is in close contact with the upper paper guide or the continuous printing paper is in close contact with the under paper guide, the printing position will not be misaligned with respect to the continuous printing paper. Similarly, no misalignment occurs due to differences in paper thickness. Also, if the paper feed direction of continuous printing paper is changed from forward to reverse,
Alternatively, even when switching from the reverse direction to the forward direction, the gap can be similarly adjusted to an appropriate value, so there is no need to change the firmware, and the effect is that a simple mechanism can be added.

Furthermore, according to the paper feeding mechanism of the second invention, the continuous printing paper can be kept in close contact with the upper paper guide by the guide ribs with appropriate pressure.
Print misalignment does not always occur. Furthermore, if the paper feed direction of continuous printing paper is changed from forward to reverse,
Alternatively, even when the direction is changed from the reverse direction to the forward direction, the same effect as the first invention can be obtained without causing any deviation.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a partial side view showing how the gap is adjusted when thin continuous printing paper is used.

FIG. 3 is a partial side view showing how the gap is adjusted when thick continuous printing paper is used.

FIG. 4 is a perspective view showing a second embodiment of the invention.

FIG. 5 is a partial side view of FIG. 4;

FIG. 6 is a partial side view showing a conventional embodiment.

FIG. 7 is a partial side view showing a conventional embodiment.

[Explanation of symbols]

1 Gap adjustment lever 2 Gear 3 Guide shaft 4 Eccentric shaft 5 Under paper guide 6 Upper paper guide 7 Print head 8 Carriage 9 Platen 10 Push tractor 11 Side frame 12 Continuous printing paper 20 Upper paper guide 21
Guide rib 22 Support plate 23 Spring

Claims (2)

[Claims] 1. A carriage on which a print head is mounted and which performs printing while moving parallel to the longitudinal direction of the platen guided by a guide shaft fixed to a side frame; and a carriage fixed to the side frame and printing by the print head. The tractor includes an upper paper guide and an under paper guide for guiding the continuous printing paper to a position, and a tractor provided on the insertion side of the continuous printing paper and having endless belts on the left and right sides for supplying the continuous printing paper. In the paper feed mechanism of a printer, the paper feed mechanism has an eccentric rotation center at both ends and is rotatably held by the side frame;
and a swingable gap adjustment lever having a first gear fixed to one end of the guide shaft, and a second gear engaged with the first gear, and rotatably held by the side frame. an eccentric shaft having a rotation center on the paper insertion side of the continuous printing paper, and the underside shaft having a rotation center on the paper insertion side of the continuous printing paper, is swingably held by the side frame, and keeps the paper discharge side of the continuous printing paper in constant contact with the eccentric shaft; A paper feeding mechanism characterized by comprising a paper guide. 2. A carriage on which a print head is mounted and performs printing while moving parallel to the longitudinal direction of the platen guided by a guide shaft fixed to a side frame; and a carriage fixed to the side frame and printing by the print head. The tractor includes an upper paper guide and an under paper guide for guiding the continuous printing paper to a position, and a tractor provided on the insertion side of the continuous printing paper and having endless belts on the left and right sides for supplying the continuous printing paper. In the paper feed mechanism of a printer, a support plate held by the side frame, a plurality of springs supported at one end by the support plate, and each supported by the other end of the plurality of springs,
A paper feeding mechanism comprising: a plurality of guide ribs facing the lower surface of the upper paper guide and having a shape that follows the upper paper guide.